As will be better understood from the following description, the present invention was developed for decreasing crew workload when interacting with an electronic checklist (ECL) system during the presence of non-normal aircraft conditions. While developed for use in this environment and described in connection with this environment, it is anticipated that the invention will also find use in other environments employing a plurality of checklists applicable to normal and non-normal operating conditions.
There are many environments in which checklists are used in an attempt to ensure safe and reliable operation of various types of equipment and systems. In some environments, such as the operation of airplanes and other complex equipment and systems, several "normal" checklists are used during different operational phases encountered when the airplane or other equipment is operating under normal conditions. Usually, these environments also employ several "non-normal" (also known as "abnormal", "irregular" or "emergency") checklists that are used when various non-normal operating conditions are encountered.
One type of checklist often used today on airplanes is a printed paper checklist, which lists checklist line items (checklist steps) on a series of cards or the pages of a book. Although simple in form, paper checklists are subject to several disadvantages and drawbacks. For example, if checklist items are skipped for later performance they may be forgotten. In addition, paper checklists do not provide an indication of checklist execution progress, i.e., they do not provide an indication of whether line items have been completed or not completed. Thus, the completion of checklist line items may be forgotten if the execution of a checklist is interrupted for any reason.
There have been various attempts to provide improved checklist systems, including devices for scrolling a paper checklist so that one checklist line item at a time is visible through a window or other opening. Electromechanical checklist systems also have been provided. Electromechanical checklists generally include a plurality of switches that correspond to various line items. In such systems, the switches are actuated to indicate completion of the corresponding line item. Checklist systems that audibly read out line items of a selected checklist also have been developed. In such systems, the pilot or other crew member typically activate a check-off switch to proceed to the next checklist item. Electronic checklist systems also have been provided, with such systems usually displaying checklist items on a cathode ray tube such as an airplane weather radar display. The checklist provided by these prior art electronic systems generally correspond to paper checklists that simply have been converted to electronic format.
An improvement over the foregoing and other previous developed systems is described in U.S. Pat. No. 5,454,074 (Hartel et al.). Hartel et al. describes a computer-based electronic checklist (ECL) system for the rapid and accurate presentation of both normal and non-normal checklists upon request by a flight crew. The normal checklists are arranged in a sequence that corresponds to the order in which the normal checklists are used during normal operation of an airplane. The non-normal checklists include checklists applicable to and associated with crew alert messages that are supplied by an airplane crew alert system in response to an associated non-normal aircraft condition. Also provided are non-normal checklists that are applicable to situations for which the airplane crew alert system does not provide a crew alert message.
FIG. 1 illustrates a typical scenario showing the steps required of a pilot using the ECL system of Hartel et al. In order for a pilot to get the desired result from the illustrated example, the pilot must maneuver through ten steps. A ten step scenario is of acceptable length provided the pilot has adequately retained training procedures of how to navigate from a non-normal checklist associated with a primary non-normal condition to non-normal checklists associated with secondary non-normal conditions and then back. In this regard, the checklist associated with the primary non-normal condition is the highest checklist in a hierarchical structure of checklists related to a group of non-normal conditions. If a primary system fails, causing the failure of secondary systems, non-normal checklists relating to all the failures are retrieved. That is, the non-normal checklist that relates to the primary system failure and the non-normal checklists that relate to the secondary system failures are all retrieved. The completion of the retrieved non-normal checklist relating to the primary system failure makes the execution of the non-normal checklists relating to secondary system failures unnecessary, because either the primary system failure was the cause of the secondary system failures or the steps performed by the non-normal checklists associated with the secondary system failures are included in the non-normal checklist relating to the primary system failure.
The exemplary scenario illustrated in FIG. 1 relates to a hydraulic system failure. When the hydraulic system of an airplane fails (a primary failure), the flight controls and stabilizer systems of the airplane become degraded (secondary failures). These failures cause crew alert messages 10, 12 and 14 and checklist status icons 18, 20 and 22 to be displayed on the display 16 of an Engine Indicating Crew Alerting System (EICAS). These displays inform the pilot what non-normal checklists are to be executed in response to the system failure. In this example, the display includes a crew alert message related to the primary failure denoted HYD PRESS SYS R+C and two alert messages related to the two secondary failures denoted FLIGHT CONTROLS and STABILIZER, respectively. While crew alert messages related to both primary and secondary failures are displayed, in reality, only the checklist related to the primary failure, i.e., the checklist related to the HYD PRESS SYS R+C crew alert message is required to be executed in response to the primary failure. A pilot seeing the crew alert messages on the EICAS display 16, will actuate a CHKL button located on a Display Select Panel (not shown) that will cause a checklist queue 28 to be displayed. This is step 1. The pilot will then select the non-normal checklist associated with the primary failure. Selection can be accomplished by highlighting or placing a cursor on the appropriate part of the display and actuating a cursor control key. This is step 2. The pilot's action causes a non-normal checklist 10b associated with the primary failure to be displayed. Next, the pilot completes the checklist. The last step of the checklist associated with the primary failure, i.e., the HYD PRESS SYS R+C non-normal checklist display 10b, is an Open Loop Action Item 30. The Open Loop Action Item 30 identifies the checklists that need to be overridden. This has the potential of creating pilot confusion.
In order to override the non-normal checklists listed in the Open Loop Action Item 30, the pilot must first select a NON-NORMAL button 32 included in the HYD PRESS SYS R+C non-normal checklist display 10b. Again, selection is accomplished by highlighting or placing a cursor on the appropriate part of the display and actuating a cursor control key. This causes the checklist queue 28 to be redisplayed. Next, the pilot selects the non-normal checklist associated with the first listed secondary failure denoted FLIGHT CONTROLS from the checklist queue 28. Selection is performed as described above. This is step 4. The pilot's action causes a non-normal checklist 12b associated with the secondary failure denoted FLIGHT CONTROLS to be displayed. Next, the pilot overrides the FLIGHT CONTROLS checklist by selecting a CHKL OVRD button 34. This is step 5.
In order to override the last non-normal checklist listed in the Open Loop Action Item 30 shown in the HYD PRESS SYS R+C non-normal checklist display 10b, the pilot must first select a NON-NORMAL button 32 included with the FLIGHT CONTROLS non-normal checklist display 12b. This is step 6. This causes the checklist queue 28a to be redisplayed with the overridden checklist not present. Next, the pilot selects the non-normal checklist associated with the other secondary failure denoted STABILIZER from the checklist queue 28a. Selection is performed as described above. This is step 7. The pilot's action causes a non-normal checklist 14b associated with the secondary failure denoted STABILIZER to be displayed. Next, the pilot overrides the STABILIZER checklist by selecting the CHKL OVRD button 34. This is step 8.
The pilot returns to the checklist queue 28 by selecting a NON-NORMAL button 32 included with the STABILIZER non-normal checklist display 14b. This is step 9. This causes the HYD PRESS SYS R+C non-normal checklist display 10c to be redisplayed with the Open Loop Action Item 30 checklist. This is step 10. At this point, all of the pilot tasks associated with this ECL system example are completed.
As will be readily apparent from the foregoing description, clearing each non-normal checklist associated with a secondary non-normal condition requires that the following four steps be performed: 1. selection of NON-NORMAL button; 2. selection of checklist from checklist queue; 3. select CHKL OVRD button; 4. selection of NON-NORMAL button.
Even though Hartel et al. is an improvement over the prior known techniques, Hartel et al. is subject to further improvement. Eliminating the need to override unnecessary non-normal checklists would decrease pilot confusion, improve crew workload during non-normal operating conditions and reduce crew training time. The present invention is directed to accomplishing this result. More specifically, the present invention is directed to decreasing crew workload when interacting with an ECL system during the presence of non-normal aircraft conditions.